# Amazon ECS clusters for Fargate
Clusters for Fargate

With Amazon ECS on AWS Fargate capacity providers, you can use both Fargate and Fargate Spot capacity with your Amazon ECS tasks. 

With Fargate Spot, you can run interruption tolerant Amazon ECS tasks at a rate that's discounted compared to the Fargate price. Fargate Spot runs tasks on spare compute capacity. When AWS needs the capacity back, your tasks are interrupted with a two-minute warning.

When tasks that use the Fargate and Fargate Spot capacity providers are stopped, the task state change event is sent to Amazon EventBridge. The stopped reason describes the cause. For more information, see [Amazon ECS task state change events](ecs_task_events.md).

A cluster can contain a mix of Fargate and Auto Scaling group capacity providers. However, a capacity provider strategy can only contain either Fargate or Auto Scaling group capacity providers, but not both. For more information, see [Auto Scaling Group Capacity Providers](https://docs.aws.amazon.com/AmazonECS/latest/developerguide/cluster-auto-scaling.html#asg-capacity-providers).

Consider the following when using capacity providers:
+ You must associate a capacity provider with a cluster before you associate it with the capacity provider strategy.
+ You can specify a maximum of 20 capacity providers for a capacity provider strategy.
+ You can't update a service using an Auto Scaling group capacity provider to use a Fargate capacity provider. The opposite is also the case.
+ In a capacity provider strategy, if no `weight` value is specified for a capacity provider in the console, then the default value of `1` is used. If using the API or AWS CLI, the default value of `0` is used.
+ When multiple capacity providers are specified within a capacity provider strategy, at least one of the capacity providers must have a weight value that's greater than zero. Any capacity providers with a weight of zero aren't used to place tasks. If you specify multiple capacity providers in a strategy with all the same weight of zero, then any `RunTask` or `CreateService` actions using the capacity provider strategy fail.
+ In a capacity provider strategy, only one capacity provider can have a defined *base* value. If no base value is specified, the default value of zero is used.
+ A cluster can contain a mix of both Auto Scaling group capacity providers and Fargate capacity providers. However, a capacity provider strategy can only contain Auto Scaling group, or Fargate capacity providers, but not both.
+ A cluster can contain a mix of services and standalone tasks that use both capacity providers. A service can be updated to use a capacity provider strategy rather than a launch type. However, you must force a new deployment when doing so.

## Fargate Spot termination notices


During periods of extremely high demand, Fargate Spot capacity might be unavailable. This can cause Fargate Spot tasks to be delayed. When this happens, Amazon ECS services retry launching tasks until the required capacity becomes available. Fargate doesn't replace Spot capacity with on-demand capacity. 

When tasks using Fargate Spot capacity are stopped due to a Spot interruption, a two-minute warning is sent before a task is stopped. The warning is sent as a task state change event to Amazon EventBridge and as a SIGTERM signal to the running task. If you use Fargate Spot as part of a service, then in this scenario the service scheduler receives the interruption signal and attempts to launch additional tasks on Fargate Spot if there's capacity available. A service with only one task is interrupted until capacity is available. For more information about a graceful shutdown, see [Graceful shutdowns with ECS](https://aws.amazon.com/blogs/containers/graceful-shutdowns-with-ecs/).

To ensure that your containers exit gracefully before the task stops, you can configure the following:
+ A `stopTimeout` value of `120` seconds or less can be specified in the container definition that the task is using. The default `stopTimeout` value is 30 seconds. You can specify a longer `stopTimeout` value to give yourself more time between the moment that the task state change event is received and the point in time when the container is forcefully stopped. For more information, see [Container timeouts](task_definition_parameters.md#container_definition_timeout).
+ The SIGTERM signal must be received from within the container to perform any cleanup actions. Failure to process this signal results in the task receiving a SIGKILL signal after the configured `stopTimeout` and may result in data loss or corruption.

The following is a snippet of a task state change event. This snippet displays the stopped reason and stop code for a Fargate Spot interruption.

```
{
  "version": "0",
  "id": "9bcdac79-b31f-4d3d-9410-fbd727c29fab",
  "detail-type": "ECS Task State Change",
  "source": "aws.ecs",
  "account": "111122223333",
  "resources": [
    "arn:aws:ecs:us-east-1:111122223333:task/b99d40b3-5176-4f71-9a52-9dbd6f1cebef"
  ],
  "detail": {
    "clusterArn": "arn:aws:ecs:us-east-1:111122223333:cluster/default",
    "createdAt": "2016-12-06T16:41:05.702Z",
    "desiredStatus": "STOPPED",
    "lastStatus": "RUNNING",
    "stoppedReason": "Your Spot Task was interrupted.",
    "stopCode": "SpotInterruption",
    "taskArn": "arn:aws:ecs:us-east-1:111122223333:task/b99d40b3-5176-4f71-9a52-9dbd6fEXAMPLE",
    ...
  }
}
```

The following is an event pattern that's used to create an EventBridge rule for Amazon ECS task state change events. You can optionally specify a cluster in the `detail` field. Doing so means that you will receive task state change events for that cluster. For more information about creating an EventBridge rule, see [Getting started with Amazon EventBridge](https://docs.aws.amazon.com/eventbridge/latest/userguide/eb-get-started.html) in the *Amazon EventBridge User Guide*.

```
{
    "source": [
        "aws.ecs"
    ],
    "detail-type": [
        "ECS Task State Change"
    ],
    "detail": {
        "clusterArn": [
            "arn:aws:ecs:us-west-2:111122223333:cluster/default"
        ]
    }
}
```

# Creating an Amazon ECS cluster for Fargate workloads
Creating a cluster for Fargate workloads

You create a cluster to define the infrastructure your tasks and services run on.

Before you begin, be sure that you've completed the steps in [Set up to use Amazon ECS](get-set-up-for-amazon-ecs.md) and assign the appropriate IAM permission. For more information, see [Amazon ECS cluster examples](security_iam_id-based-policy-examples.md#IAM_cluster_policies). The Amazon ECS console creates the resources that are needed by an Amazon ECS cluster by creating a CloudFormation stack. 

The console automatically associates the Fargate and Fargate Spot capacity providers with the cluster.

You can modify the following options:
+ Add a namespace to the cluster.

  A namespace allows services that you create in the cluster can connect to the other services in the namespace without additional configuration. For more information, see [Interconnect Amazon ECS services](interconnecting-services.md).
+ Enable task events to receive EventBridge notifications for task state changes.
+ Add tags to help you identify your cluster.
+ Assign an AWS KMS key for your managed storage. For information about how to create a key, see [Create a KMS key](https://docs.aws.amazon.com/kms/latest/developerguide/create-keys.html) in the *AWS Key Management Service User Guide*.
+ Assign an AWS KMS key for your Fargate ephemeral storage. For information about how to create a key, see [Create a KMS key](https://docs.aws.amazon.com/kms/latest/developerguide/create-keys.html) in the *AWS Key Management Service User Guide*.
+ Configure the AWS KMS key and logging for ECS Exec.

## Procedure


**To create a new cluster (Amazon ECS console)**

1. Open the console at [https://console.aws.amazon.com/ecs/v2](https://console.aws.amazon.com/ecs/v2).

1. From the navigation bar, select the Region to use.

1. In the navigation pane, choose **Clusters**.

1. On the **Clusters** page, choose **Create cluster**.

1. Under **Cluster configuration**, configure the following:
   + For **Cluster name**, enter a unique name.

     The name can contain up to 255 letters (uppercase and lowercase), numbers, and hyphens.
   + (Optional) To have the namespace used for Service Connect be different from the cluster name, under **Service Connect defaults**, for **Default namespace**, choose or enter a namespace name. To use a shared namespace, choose or enter a namespace ARN. For more information about using shared namespaces, see [Amazon ECS Service Connect with shared AWS Cloud Map namespaces](service-connect-shared-namespaces.md).

1. (Optional) Use Container Insights, expand **Monitoring**, and then choose one of the following options:
   + To use the recommended Container Insights with enhanced observability, choose **Container Insights with enhanced observability**.
   + To use Container Insights, choose **Container Insights**.

1. (Optional) To enable task events, expand **Task events**, and then turn on **Enable task events**.

   When you enable task events, Amazon ECS sends task state change events to EventBridge. This allows you to monitor and respond to task lifecycle changes automatically.

1. (Optional) To use ECS Exec to debug tasks in the cluster, expand **Troubleshooting configuration**, and then configure the following:
   + (Optional) For **AWS KMS key for ECS Exec**, enter the ARN of the AWS KMS key you want to use to encrypt the ECS Exec session data.
   + (Optional) For **ECS Exec logging**, choose the log destination:
     + To send logs to CloudWatch Logs, choose **Amazon CloudWatch**.
     + To send logs to Amazon S3, choose **Amazon S3**.
     + To disable logging, choose **None**.

1. (Optional), Under **Encryption**, you can configure the following:
   + Encrypt your data on Fargate ephemeral storage. Under **Encryption**, for **Fargate ephemeral storage**, enter the ARN of the AWS KMS key you want to use to encrypt the Fargate ephemeral storage data.
   + Encrypt the data on managed storage. Under **Encryption**, for **Managed storage**, enter the ARN of the AWS KMS key you want to use to encrypt the managed storage data.

1. (Optional) To help identify your cluster, expand **Tags**, and then configure your tags.

   [Add a tag] Choose **Add tag** and do the following:
   + For **Key**, enter the key name.
   + For **Value**, enter the key value.

   [Remove a tag] Choose **Remove** to the right of the tag’s Key and Value.

1. Choose **Create**.

## Next steps


After you create the cluster, you can create task definitions for your applications and then run them as standalone tasks, or as part of a service. For more information, see the following:
+ [Amazon ECS task definitions](task_definitions.md)
+ [Running an application as an Amazon ECS task](standalone-task-create.md)
+ [Creating an Amazon ECS rolling update deployment](create-service-console-v2.md)